Power actuator



Julie 30, 1931. c, s, BRAGG ET AL 1,811,994

POWER ACTUATOR Filed Nov. 5, 1925 3 Sheets-Sheet 1 2a 25 5 31 M a ATTORNEY Jfine 30, 1931; c. s. BRAGGVET A L POWER ACTUATOR Filed Nov. 5, 1925 3 Sheets-Sheet 3 QQNG .3

Patented June 30, 1931 stares PATENT oer-"ice CALEB S. BRAGG, GE PALM BEACH, FLORIDA, AND VICTOR W. KLIESRATH, OF PORT WASHINGTON, NEW YORK,

LONG ZSLAND CITY, KEV] YGRK, A CORPORATION OF NEW YORK rowan ACTUATOR Application filed November 5, 1925. Serial No. 66,961.

Our invention consist-s in the novel features hereinafter described, reference being bad to the accompanying drawings which illustrate one embodiment of the invention, selected by us for purposes of illustration, and the said invention is fully disclosed in the followlng description and claims:

application for Letters Patent of, the United tates, filed December 22, 1923, Serial No.

682,3 l6, we have discloseda power actuator of this general type, connected with the intake manifold of the internal combustion engineby means of a pipe or passage in which are located an adjustable regulating valve or other restricting means, "a check valve, and a storage space or tank, and comprising a cylinder, a double acting piston therein, and reversing valve mechanism for applying differential pressures'on opposite faces of the piston, said actuator being combined with a foot lever or other operator operated part and with a brake mechanism or other part to be actuated, in such manner that the latter can be operated by the actuator under the control of the foot lever, while the operator may also add his physical power to the power of the actuator when desired, or in case of failure of power, may positively operate thev actuated part by physical power applied to the foot lever or other operator operated part.

As the suction passage of the internal combustion engine draws in through the carburetor and delivers to the cylind rs an explosive mixture of air and fuel,'in pre-determined proportions, under the control of the throttle-valve, any device connected withthe intake manifold, so as to discharge into it suddenly a large volume of atmospheric air, would have the effect of decreasing the degree of rarification 1n the suction passage and changing the proportions of air and fuel therein, either by diluting the mixture pass- ASSIGIQ'GRS TO BRAGG & KLIESRATH CORPORATION, 0F 7 ing through such passage, or preventing the delivery from the. carburetor of the requisite quantities of fuel, and in either case, the result would be to interfere with the desired operation of the engine under the control of the throttle valve, and to stall the engine if idling.

In the apparatus of our former application, we employed a restricting valve in the suction pipe or passage between the actuator and the suction passage of the engine, for the purposeof preventing the too rapid delivery of large quantities of air withdrawn from the actuator, into said suction passage, and to distribute saidair gradually over a more extended period of time, to avoid interfering with the operation of the engine or stalling the engine if idling, and we provided a storage space which would normally be maintained in an exhausted condition, interposed between the suction passage and the actuator,

to insure an immediate response of the actuatorfor the actuation of brakes or other acvide means for normally mainta ning a state of r arification within the cylinder of the actuator itself, on both sides of the piston, when the'latter is in the normal or off position, thereby dispensing with an extraneous storage space and providing a construction in which the operation of the reversing valve mechanism, to effect the operation of the piston in a direction to apply the brakes or operate other devices to be operated, will be effected by the admission of atmospheric air (or other higher pressure fluid) in rear of the piston, so that its operative movement is effected without admitting any appreciable quantity of air to the suction passage of the engine, and we dispense with a regulating valve in'the suction pipe or passage between the actuator and the suction passage of the engine, and provide reduced passages of less cross sectional area than the normal working ing the cylinder on both sides of the piston with the suction pipe or passage, so that whenever atmospheric air (or other higher pres sure fluid) previously admitted to the cylinder on either side is to be withdrawn from the cylinder, such withdrawal will be restricted or throttled by said passages of reduced area, while the valves may be opened to provide communicationpassages of greater area whenever it is necessary to effect a working stroke of the piston. The effect of this construction is to supply a restricting means for preventing too rapid discharge of air into the suction passage of the engine, (with the consequent and necessarily resulting slight delay or retarding of the operation of the piston) during the return stroke of the pis ton, as in releasing the brakes or other parts to be operated while no restiiction is provided when instantaneous response of the piston is needed, as in making stroke for the application of brakes or other devices to be operated. For example, if the cylinder is wholly filled with air, as after long periods of non-use, or when it is partially lilledwith air due to a recent operation of the brake mechanism, the said reduced openings normally connecting the cylinder on both sides of the piston with the suction pipe, serve to restrict the exhaustion of the air from the cylinder and cause it to be delivered more slowly and gradually into the intake manifold with an effect somewhat similar to that which would be produced by the presence of a restricting or regulating valve in the suction pipe, but if, for example, immediately after the application of the brake mechanism, and before the air admitted to the cylinder for that purpose had been fully exhausted, it should become necessary to instantly apply the brakes again, the operation of the valve mechanism would supply an unrestricted passage of greater area, to the manifold or suction passage, and insure the instantaneous response of the piston to apply the brakes, without the retarding influence which the restricting valve of our former application would exercise, were it present in the construction. In other words, we produce by our present invention, a restricting effect on the discharge of air into the suction passage of the engine whenever its slightly retarding ef ect will not be prejudicial to the operation of the mechanism, while no restriction is effected whenever the prompt and instantaneous operation of the piston, to effect the application of the brakes, is required, and we dispense with a restricting or regulating valve in the suction pipe or passage.

In order that our present invention may be clearly understood, we have illustrated one embodiment of the same in the accompanying drawings, in which Fig. 1 is a diagrammatic view representing an installation of our improved power actuator in connection with the internal combustion engine of an automotive vehicle, for the operation of the brake mechanism of the vehicle.

Fig. 2 is an enlarged sectional view illustrating one form of our improved actuator having our invention embodied therein, and showing the reversing valve mechanism and the piston in their normal or off position.

Fig. 3 is an enlarged view of the piston hub and reversing valve mechanism shown in Fig. 2, as it would appear in the normal or ofi position and in the neutral position.

Fig. 4 is a similar view showing the positions of the valve, when operated to effect a power stroke of the piston to apply the brakes.

Fig. 5 is a View similar to Figures 3 and 4, showing the position of the valve mechanism when operated to produce the return movement of the piston to its normal or off position.

Fig. 6 is a sectional view of a portion of the actuator showing a modified form of valve mechanism, the valves being shown in normal or off position.

Fig. 7 is a similar view of the parts illustrated in 6, showing the position occupied by the valves in making a power stroke of the piston.

In Fig. 1 of the accompanying drawings, we have shown diagrammatically an installation suitable for use in an automotive vehicle, in which our improved actuator is shown interposed in the connection between a foot lever, 88, and brake mechanism for the vehicle, diagrammatically represented at 70, 1 and 72, which indicate, respectively, a brake drum, brake band and brake lever, but it is to be understood that our invention is applicable to any form of brake mechanism. 60 represents an internal combustion engine for propelling the vehicle, provided with an intake manifold indicated at 61, connected with the carburetor, 63, and controlled by a throttle valve, 64, in the usual or any preferred manner. 62 represents a suction pipe, portions of which are flexible, for connecting the suction passage of the engine, between the throttle valve and the cylinders, as the intake manifold, 61, with our improved power actuator, said pipe being preferably provided with a check valve indicated at 65,

.15 and 16.

the actuator cylinder. The suction pipe, 62, is in this instance connected to a hollow valve actuating sleeve, 20, communicating with and v(uperating by'longitudinal movement of the sleeve, the reversing valve mechanism. The sleeve, 20, is connected by a link, 85, with the foot lever, 88, which may be provided with the usual retracting spring, 89,

provided with oppositely disposed gaskets,

l-4.- 5 represents a hollow piston rod extending through a stuffing box, 6, in one end of the cylinder, and represents another hollow piston rod extending in the opposite direction through the other cylinderhead and through a stuffing box, 6 therein. The

piston rod, 5, is shown provided with a cap, 8, havlng an attaching lug, 9, for connecting it with the link, 73. lhe hub, 10, or" the actuator piston is provided with two valve chambers, 11 and 12, eaclrof which is provided with two oppositely disposed valve seats, preferably conical, and co-axial with the piston. -/hamber 11 contains the seats 13 and 1 1, and chamber 12 contains the seats The valve chamber, 11, is connected between its valve seats, by a port or ports, 84, with the cylinder on one side of the piston, and the valve chamber, 12, is similarly connected with the cylinder on the other side of the piston, by the port or ports, 36, between the valve seats.

The hub, 10, is provided with anoutlet or suction chamber, 17, which communicates with both of the adjacent valve chambers through the valve seats, 1% and 15, under the control of the valvemecha-nism hereinafter described. Provision is also made for admitting'a higherpressure fluid, as atmospheric air, to each of the valve chambers under the control of the valve mechanism,

, and in this instance the piston rod, 5,- is provided with an air inlet aperture, 31, in the cap, 8,.adapted to communicate, as herein after described, with the valve seat, 16, while the piston rod, 5 is provided at its out-er end with an air inlet aperture, 31, communicating with, the valve seat, 13. 2O repre sents a valve actuating sleeve passing longitudinally through the piston rods, 5 and 5, andthrough the hub. of the )iston, co-axially with the valve seats therein, said sleeve being longitudinally movable as hereinafter de scribed, to eii'ect the operation of the reversing valve mechanism. The valve actuating sleeve is provided with an interior-plug or partition, 23, and the portion at one side of the plu or partition, (at the left in Fig.

2) is connected by lateral apertures, 24, with the suction chamber, 17.. This end of the valve actuating sleeve extends outside of the cylinder beyond the end of the piston roe,

5, and is connected with the outlet or suction pipe, 62, previously mentioned. The valve actuating sleeve is also provided with mcansitor connecting with the foot lever or other operator operated parts, and in tl is instance it is shown as provided with a perforated lug, in which thelink, 85, extending through the foot lever, I is connected. The flexible portions of the suction pipe, 62, permit the longitudinal movement or the valve actuating sleeve. The end portion of the sleeve, 20, beyond the plug, 23, (at the right in Fig. 2) is also conveniently provided with apertures, indicated at 2st", so that the atmospheric air entering through the aperture, 31,

may pass longitudinally of the sleeve to the valve chamber, 12, under the control of the valve mechanism. e 7

- ljVithin each of the valve chambers, 11 and 12, the valve actuating sleeve is provided with a pair of oppositely disposed valves, preterably conical, and engaging'the opposite valve seats betoredescribed, said valves being located between valve engaging and oper ating collars with which the sleeve is provided. necessarily,- iormed of molded rubber, and

are mounted on the valve, actuating sleeve in such manner as to permit the sleeve to move through them while sealing the opening in the valve throughwhich the actuating sleeve passes, and said valves are also provided with means tor yieldingly pressing them toward their seats. In the present instance, we have shown the valve actuatmg sleeve, 20, pro? vided within the valve chamber, 11, with oppositely disposed valves, 10 and ll, engaging the seats, 13 and 14, respectively, and within thevalve chamber, 12, with the oppositely disposed valves, 42 and 1%, engaging the seats,

These valves are preferably, but not 15 and 16, respectively. Each valve is prof,

vided with central aperture whichfits the valve actuating, sleeve ti 'htly while permitting the longitudinal movement of the sleeve therethrough, and said valves are'yieldingly pressed toward their seats, inthis instanceby spring washers, indicated generally at. 50, the specific construction of which does not constitute anypart of our present invention and will not be further or more particularly described. vided with an actuating collar for each valve, which collars are indicated at 40 11, 42, and d3.

In order to provide for the exhaustion of the cylinder on both sides of the pistonwhen the piston is in normal or on position, 'in which'it is shown in Fig.2, means are pro vided for arresting the valve actuating'sleeve at a pre-determined point, and the collars, 4:1 and 42', are solocated on the valve-actu The valve actuating sleeve is proating sleeve that the central valves, 41 and 42, which are on opposite sides of the suction chamber, 17, will be held slightly ofi of their seats when the partsare in the off or normal 5 position, thereby providing passages of much smaller cross sectional area than the passages between said valves and the seats when fully opened, connecting the suction passage with the cylinder on both sides of the piston, as clearly shown in Fig. 2. For the purpose of arresting the sleeve, 20, so as to hold the valve, 41 and 42 in this partially open position, the sleeve, 20, is preferably provided with a collar, 21, adjustably secured thereto, as by being threaded thereon and secured by a set screw, 21a, for example, said collar, 21, being so located that it will engage the outer end of the adjacent head, 2, of the actuator cylinder just before the piston comes to rest 20 in its off position, and the collars, 41 42, are so located, that when the piston comes to rest with its hub against the other cylinder head, the valves, 41 and 42 will be held in slightly or partially open position. At this time, the valves 40 and 43 will be firmly seated, as shown in Fig. 2, and the collars, 40 and 43, which control these valves, are spaced slightly away from their respective valves, so that they will not engage the same until the valve sleeve, 20, has moved far enough to permit the seating of the oppositely disposed valve in the same valve chamber. It will be seen that this construction will effect the rarification of the cylinder on both sides of 35 the piston when the latter is in the off position, and the throttle valve of the engineis in closed position, or has been closed, so as to provide normally a rarified condition within the suction passage or manifold of the in vacuum. It will also be seen that whenever the valves are in the position previously described and illustrated in Fig. 2, that is to say, the valves 41 and 42 on opposite sides of the suction chamber, 17, being slightly or partially open, the communicating openings thus produced by the partially openposition of valves, 41 and 42, provide a restricted passage which is in fact much smaller in cross sectional area than the capacity of the interior of the valve actuating sleeve, 20, and

engine, and the piston is therefore submerged and there is no restriction, a restricting valve being employed as in application 682,346.

To maintain the highest possible degree of rariiication'within the cylinder on both sides of the piston, we prefer to employ a check valve between the intake manifold and the reversing valve mechanism, which is preferably located in the suction pipe or passage, as indicated at 65, so that the high degree of rarification obtained in the manifold will be imparted to the cylinder, between operations of the actuator, and the degree of rarification within the cylinder is prevented from varying with the variations which take place within the manifold, as the throttle valve is opened and closed.

Assuming that the internal combustion engine is in operation or has been operating with the throttle valve closed or substantially closed, it will be seen that the air will be exhausted from the suction passage, 62, and from the actuator cylinder on both sides of the piston, and that the air so withdrawn from the cylinder through the restricted passages provided in this instance by the partial opening of valves 41 and 42 of the reversing valve mechanism will have been distributed into the intake manifold gradually so as to prevent interference with the operation of the engine or the danger of stalling it if idling, and the apparatus is in condition for immediate and instantaneous use to apply the brakes, as the checkvalve retains the state of rari fication within the actuator cylinder, as before described. In order to apply the brakes, the operator will operate the foot lever, thereby moving the valve actuating sleeve in the direction of the arrow in Fig. 2. The first ef fect of this movement of the valve sleeve will be to permit the partially open valve, 42, to seat, and the valve'41 to open further, after which, the collar, 43, will engage the valve 43 and open it, thus continuing the connection between the cylinder forward of the piston (at the left in Fig. 2) with the suction chamher, and admitting atmospheric air through the hollow piston rod, 5, to the actuator cylinder on the opposite side of the piston. As a condition of rarification exists in the cylinder forward of the piston, the atmospheric pressure admitted to the valve, 43, exerts a force on the rear face of the piston, causing it to move forward, applying the brakes, without admitting any appreciable amount of air into the intake manifold from the portion of the cylinder forward of the piston. When the operator stops the movement of the brake pedal or lever, the slightest continued movement of the piston causes the valve, 43, to engage its seat and shut off the source of pressure. When the operator desires to gradually release the brakes, as in continued braking on long grades or in traflic, he slightly releases the brake lever, permitting it to move backward slightly, under the action of the retracting spring, thus closing valve, 43, par-. tially closing valve, 41, and slightly opening valve, 42, again connecting both ends of the cylinder with each other and with the suction chamber and effecting an immediate equalize,

tion of pressures within the cylinder, com-t bined with the withdrawal of the air ,previously admitted, to applythe brakes, which is again distributed into the manlfold gradually under the restricting action of the partially open valves, 41 and 42, providing, as before stated, passages of smaller area than are provided by either valve when in open position. Therefore, the piston may be readily moved rearwardly by the load of the applied brake bands or shoes for the release thereof, without admitting any atmospheric pressure to the cylinder forward of the piston. In making a subsequent application of the brakes from this position, the operator moves his foot forward, again moving the valve actuating sleeve forward, permitting the valve, 42, to close, further opening valve, ll, maintaining the connection between the cylinder forward of the piston (at the left inFig. 2 and the intake manifold by a suction pipe or passage in which there is no restricting device, the valve, 43, being also simultaneously opened to admit air under atmospheric pressure in rear of the piston, so that the brakes will be again and instantly applied. This operation of releasing the brake mechani'sin without admitting any additional air forward of the piston, and reapplyin'g the;

brakes, may be repeated as often as necessary, as on a long grade or when driving in traffic, and each time the brakes are applied, the suction passage will be without restriction or retarding effect, while each time the brakes are released, the valve, 41, and the valve, 42, will be brought into partially open position and restrict the suction passage.

hen the operator removes his foot from the brake pedal, the retracting spring forces the valve actuating sleeve rearwardly (in the direction opposite to that indicated by the arrow in Fig. 2), the first movement of. the valve actuating sleeve with respect to the piston partially closing valve, 41, and opening valve, 42, effecting simultaneously an equalization of pressures within the cylinder on both sides of the piston, and the withdrawal of the air previously admitted to apply the brakes which permits the draught of the applied brakes to move the piston rearwardly at the same speed that the valve actuating sleeves moves until the brakes are released, at which time the valve actuating sleeve will move faster than the piston, under the, action of the retracting spring, and will close valve, l1, and will open further valve, l2, and will open the air inlet valve, 40, continuing the connection between thecylinder in rear of the piston, with the vacuum chamber, and admitting atmospheric air to the cylinder forward of the piston and positivelyreturning it and thebrake mechanism to the normal or off position by power. The piston is arrested in such position by its hub coming in contact withthe end ofthe cylinder and just previous tothearrest of the piston, the collar,

21, of the valve actuating sleeve, comes in contact with the opposite end of the cylinder,

arresting the sleeve before the pistoncomes to rest. 7 I

piston with respect to t to sleeve, which follows the arrest of the sleeve, 20, restores the valves, l and l2, to the partially open position, again providing restricted openings communicating with the suction passage and restricting the delivery of the air just now exhausted from the cylinder forward of the piston, and which produced the rearward movement of the piston, so as to'prevent interference with the operation of the and the stalling thereof, if idling.

This is important, as it does notmatter if there is a retarding effect in the releasing movement of the brake mechanism, but itis important that there should be no retarding effect when the brakes are moved in a direction to apply them. It will be noticed that by our novel construction, we secure the restrict? ing effect on the suction passage when it is desired, without having it when the actuator is rom the actuator cylinder, with its consequent and necessary retardingefiect whenever the brakes are moving in adirection to release. them, while permitting the suction passage between the cylinder and the intake tently applying the brakes, will be instanta neously effected without restriction of the suction passage leading to the manifold, and

also without withdrawing-any large quantities of air from the cylinder, and without delivering any large quantities of air to the 'inanifold, while on the return of the piston to normal position, or when the engine is first started and material quantities of air must The sliglitrelativemovement of the engine r turningit to normal position for intermit stricting action on the withdrawal of air n anifold to operate at its full capacity, with- H outrestrictlon, when the brakes are to be apbe xhausted from the cylinder-on both sides of the piston, the suction passage leading to the manifold is placed under restriction to prevent interference with the operation of the engine or the stalling of the same, and at these times, any retarding effect incident to such restricting action is not disadvantageous.

It is also to be understood that according to our present invention, the suction pipe or passage, between the reversing valve mechanism and the intake manifold (or other suction means) is unrestricted, that is to say, it is not provided with any restricting means and the only restriction of this passage is that effected by the means employed for connecting the cylinder on both sides of the piston with the suction means, which is not called into action when the reversing valve mechanism is operated so as to apply the brakes.

in the particular embodiment of our invention herein shown and described, and which is our preferred construction, the restricted passages which establish communication between the suction passage and the cylinder on both sides of the piston, when the valve mechanism is in neutral position, or when the piston and the valve mechanism are in 05 position, are produced by the partial opening of the suction valves forming part of the reversing valve mechanism. /Ve desire to have it understood, however, that the inventi on is not limited to this specific construction, but is applicable to any equivalent construction in which the cylinder on both sides of the piston is connected with the suction means, when the reversing valve mechanism is in normal or neutral position by restricted passages of smaller area or capacity than the normal valve controlled apertures, when in normal or working position, to apply the brakes, whether such restricted passages are produced by partial operation of the suction valves forming part of the reversing valve mechanism or are produced by the opening of other valves or passages, to produce the same effect.

Vi e further desire to have it understood that the term unrestricted as applied to the connecting pipe or passage between the intake manifold or other suction means, and the cylinder, is intended to indicate that such passage is of substantially the capacity of the passage afforded by the suction valves when in their fully opened or normally opened condition, without any means for specifically restricting the capacity of said passage to less than the capacity of said valved openings.

It is also to be understood that we prefer to provide the actuator with means for connecting the operator operated part with the piston, containing a provision for lost motion. In this instance we have shown the outer. end of the valve actuating sleeve (at the right in Fig. 2) provided with. a collar, 25, located between the outer end of the cap, 8, and collar, 26, extending inwardly from the hollow piston rod, 5, which permits the operator to add his physical force to that of the actuator in applying the brakes when desired, and also to directly operate the actuator piston and the brake mechanism connected therewith, in case of failure of power for any reason.

In Figs. 6 and 7, we have shown a modified form of valve mechanism, in which the air inlet valve, on the forward side of the piston, is never opened to admit atmospheric air or other higher pressure fluid, but on the contrary, remains always seated and performs the function merely of sealing the annular space between the piston hub and the valve actuating sleeve within the valve seat which said valve engages.

In these figures, the various parts which correspond with those of the other figures, are given the same numerals with the addition of 100. Thus, 103 represents'the piston, the hub of which is constructed exactly as indicated in Figs. 2 to 5, and provided with the valves, 1 10, 14:1, 1 12 and 148, and yielding seating means, 150, interposed between the respective pairs of valves. 120 represents the valve actuating sleeve, also constructed as hereinbefore described, with the single exception that no provision is made for operating valve, 140, while the valve sleeve is provided with collars, 141 142 and 143, for operating the other valves in the manner hereinbefore described. The piston rod, 105, is also provided with a cap, 108, an attaching lug, 109, and the valve sleeve, 120, extends into saidcap and is provided with a collar, 125, adapted to engage a collar, 126, extending inwardly from the hollow piston rod, 105, when the valve actuating sleeve is moved in the direction of the arrow in Fig. 6. This permits the operator to apply his physical force to the piston, in order to add it to the force exerted by the actuator whendesired, and also to operate the actuator piston and the valve mechanism connected therewith, in case of failure of power. In this instance, we dispense with a stop collar on the valve actuating sleeve, 120, such as the collar, 21, shownin Fig. 2, but it will be understood that a suitable retract-ing spring will be provided for the valve actuating sleeve and pedal lever, which may be attached to the pedal lever in the same manner as the retracting spring in Fig. 1, for example, or any other form of retracting spring may be employed. In the absence of the stop collar above referred to, the retracting spring normally tends to move the valve sleeve with respect to the piston in a direction opposite that indicated by the arrow in Fig; 6, and such relative movement in such direction will be limited in this instance by the engagement of the collar, 125, or the end of the valve actuating sleeve, or both, with the end face of the cap, 108, and the valve actuating collars, 141 142 and 143 are so arranged that when the valve sleeve is so arrested, whether the piston is in the off or normal position, or in any other position in the cylinder, the valves will be held in the position indicated in Fig. 6, that is to say, the suction valves, 141 and 142, will both be held slightly open to form restricting passages communicating with the suction pipe, (not shown in this figure) through the suction chamber, 117, and the apertures, 124, in the valve actuating sleeve, 120, the valve, 143, being held closed to shut oflf the further admission of atmospheric air or other higher pressure fluid, and the collar, 143 for operating said air inlet valve, being located at a slight distance from the valve, 143 in this position of the valve actuating sleeve. As before stated, the valve, 140, always remains closed and merely serves as a sealing means. In the operation of this form of valve mechanism, when the operator desires to apply the brake mechanism, he will depress the pedal lever, so as to move the valve actuating sleeve in the direction of the arrow (Figs. 6 and 7), permitting the valve, 142, to close, opening the valve, 141, to a greater extent, and opening the air inlet valve, 143, as shown in Fig. 7, with the result that atmospheric air or higher pressure fluid enters the cylinder in rear of the piston and produces an immediate forward movement of the piston in the direction of the arrow, to apply the brakes with the full force of the apparatus, but without delivering any material amount of air to the intake manifold. On the release of the foot lever, the retracting spring will return the parts to the position indicated in Fig. 6, permitting the inlet valve, 143, to close and shut off further communication with the atmosphere, and holding both suction valves, 141, 142, in a slightly open position, permitting an immediate equalization of pressures within the cylinder on opposite faces of the piston. This permits the brakes to instantly release themselves, while the air previously admitted to the cylinder in rear of the piston, to edect the working stroke, is withdrawn and delivered to the intake manifold under the restricting action of the partially open suction valves, 141 and 142. If the return movement of the pedal lever is arrested, the slight rearward movement of the piston which follows, will again effect the slight relative movement of the piston with respect to the valve actuating sleeve, suficient to close the suction valve, 142 and crack or partially open the air inlet valve, 143, to admit sufficient atmospheric air to hold the piston and the brakes in that position, while if the operator removes the same as in the former valve mechanism previously described, except that no atmospheric air is admitted at any time to the cylinder forward of the piston, and the valve,

140 which alwa sreinains closed mereh acts to seal the interior of the piston hub against access of atmospheric air or higher pressure fluid to the cylinder forward of the piston.

T 7 V L L T 1.

id hat we ciaim and desire to secure by metters Patent is 1. In a brake system for automotive vehicles having an internal combustion engine provided with throttle controlled suction passage, the combination with a power actu ator including a cylind r closed at both ends,

a piston in said cylinder, a normally unre stricted passage from the suction passage to the cylinder, means including the piston hub and valve members for connecting the cylinder on both faces of the piston with the suc tion passage by restricted passages when the piston is in normal or off position, to submerge the piston in vacuum, and gradually deliver the air withdrawn from the cylinder to said suction means, and for connecting the cylinder on one face of the piston with said suction passage by an unrestricted passage of greater area than said restricted passages,

and admitting higher pressure fluid to the cylinder on the opposite face of the piston,

to eifect a non-retarded movement of the piston without admitting material quantities of airto the suction passage. I

2. In a brake system for automotive vehicles having an internalcombustion engine provided with a throttle controlled suction passage, the combination with a power actuator including a cylinder closed at both ends,

a piston in said cylinder, a normally unrestricted passage from the suction passage to the cylinder, an inlet for supplying higher pressure fluid to the cylinder, reversing valve mechanism movable with and with respect to the piston constructed to connect the cylinder on one face of the piston with the suetion passage, and the portion on the opposite face of the piston with the higher pressure fluid inlet, and means including a part of said valve mechanism for connecting the cylinder on both faces of the piston with the suction passage, by restricted passages of less area and capacity than the normal passages controlled by said valve mechanism when fully opened, to'temporarily restrict said suctlon passage and gradually dlstribute the an Withdrawn from the eyhnder lnto the suctlon means.

In testimony whereof we afiix our signatures.

CALEB S. BRAGG. VICTOR W. KLIESRATH. 

